A thermal conductive silicone grease with high thermal conductivity and low thermal resistance and its preparation method

Abstract

The present invention belongs to the technical field of thermal interface materials, and discloses a thermal conductive silicone grease with high thermal conductivity and low thermal resistance and a preparation method thereof. The raw material composition of the thermal conductive silicone grease is as follows: 5-10 parts of vinyl-terminated silicone oil, 0.1-1 part of side hydrogen-containing silicone oil, 0.5-5 parts of hydrogen-terminated silicone oil, 0.5-2 parts of modified silicone oil, 0.1-1 part of antioxidant, 0.01-0.2 part of catalyst, 0.01-0.2 part of inhibitor, 0.2-1 part of coupling agent, 65-85 parts of aluminum powder, and 15-25 parts of zinc oxide. By using multifunctional and multi-functional group modified silicone oil, the present invention improves the dispersibility, fluidity and interfacial wettability of powder, and reduces the interfacial thermal resistance. In addition, the side hydrogen-containing silicone oil and the hydrogen-terminated silicone oil react with the main vinyl-terminated silicone oil, enabling the silicone oil molecules to have a certain chain extension and crosslinking, improving the anti-cracking ability, and being able to well absorb the stress generated by interfacial warping to prevent interfacial delamination.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal interface materials, and particularly relates to a thermal conductive silicone grease with high thermal conductivity and low thermal resistance and a preparation method thereof. Background Art

[0002] Due to its ultra-low adhesive layer thickness, ultra-low thermal resistance, low cost and convenient use, thermal conductive silicone grease is widely used in various high-power electronic components with serious heat generation. However, for such high-power electronic components, when operating, they generate serious heat and the temperature rises rapidly, or when installed in a cold environment, it will cause the silicone grease to work in a cycle under the condition of alternating hot and cold.

[0003] Traditional silicone grease is physically blended into a paste by silicone oil and thermal conductive powder. However, the thermal expansion coefficients of high-molecular silicone oil and thermal conductive powder vary greatly. During the process of thermal cycling (temperature cycling), the silicone oil molecular chains move under the stress of thermal expansion and contraction, which easily leads to oil-powder separation. In addition, due to the different materials and large areas of the two interfaces (electronic components and heat sinks) where the silicone grease is applied, during the temperature cycling process, due to thermal expansion and contraction, the two materials warp repeatedly, squeezing the silicone grease in the middle layer repeatedly, resulting in the silicone grease being pumped out. The above two points will cause the silicone grease to become dry, powdered, cracked, and delaminated at the application interface, greatly increasing the thermal resistance of the two interfaces, reducing the heat dissipation effect, thus causing the temperature of high-power electronic components to be too high and reducing the service life. For example, Patent CN111154271A discloses a thermal conductive silicone grease, which is obtained by physically mixing thermal conductive powder and high-molecular silicone oil, and its thermal conductivity is between 4.5 and 5 W / m·K. Although it has a relatively high thermal conductivity, it is prone to problems such as a decrease in thermal conductivity and silicone grease being pumped out during long-term use, seriously reducing the thermal conductivity of the silicone grease.

[0004] Therefore, how to improve the thermal conductivity of thermal conductive silicone grease, improve its stability during use, and increase the binding force between silicone oil and powder plays an important role in the application of thermal conductive silicone grease in the field of electronic components. Summary of the Invention

[0005] The purpose of the present invention is to provide a thermal conductive silicone grease with high thermal conductivity and low thermal resistance and a preparation method thereof, to solve the problems that the oil and powder inside the traditional thermal conductive silicone grease are prone to separation after long-term temperature cycling, and the repeated warping of electronic components and heat dissipation devices causes the thermal conductive silicone grease to become dry, powdered, cracked, delaminated, etc., seriously affecting the timely dissipation of heat from electronic components, thus leading to the burnout of components.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a thermal conductive silicone grease with high thermal conductivity and low thermal resistance, which is prepared from raw materials comprising the following mass fractions:

[0008] 5 to 10 parts of terminal vinyl silicone oil, 0.1 to 1 part of side hydrogen-containing silicone oil, 0.5 to 5 parts of terminal hydrogen-containing silicone oil, 0.5 to 2 parts of modified silicone oil, 0.1 to 1 part of antioxidant, 0.01 to 0.2 part of catalyst, 0.01 to 0.2 part of inhibitor, 0.2 to 1 part of coupling agent, 65 to 85 parts of aluminum powder, and 15 to 25 parts of zinc oxide.

[0009] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the viscosity of the terminal vinyl silicone oil is 100 to 200 mPa·s, and the vinyl content of the terminal vinyl silicone oil is 0.1 to 0.5 mmol / g.

[0010] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the viscosity of the side hydrogen-containing silicone oil is 200 to 1000 mPa·s, and the hydrogen content of the side hydrogen-containing silicone oil is 0.25 to 0.35 mmol / g.

[0011] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the viscosity of the terminal hydrogen-containing silicone oil is 20 to 500 mPa·s, and the hydrogen content of the terminal hydrogen-containing silicone oil is 0.5 to 1.5 mmol / g.

[0012] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the viscosity of the modified silicone oil is 100 to 600 mPa·s.

[0013] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the modified silicone oil is a terminal-side graft-modified silicone oil, and the functional groups of the terminal-side graft are one or more of vinyl, long-chain alkyl groups with 6 to 16 carbons, acrylate groups, methoxy groups, methacryloxy groups, epoxy groups, and 3-glycidylpropyl groups;

[0014] When the functional groups of the terminal-side graft are multiple, the functional groups are vinyl, long-chain alkyl groups with 6 to 16 carbons, acrylate groups, and methoxy groups; or vinyl, methoxy groups, long-chain alkyl groups with 6 to 16 carbons, and methacryloxy groups; or vinyl, methoxy groups, epoxy groups, and 3-glycidylpropyl groups; or methoxy groups, long-chain alkyl groups with 6 to 16 carbons, methacryloxy groups, and 3-glycidylpropyl groups.

[0015] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the aluminum powder is a mixture of spherical aluminum powder with a diameter of 0.5 to 3 μm and spherical aluminum powder with a diameter of 7 to 14 μm in a mass ratio of 1:2 to 1:4.

[0016] Preferably, in the above-mentioned heat-conducting silicone grease with high heat conductivity and low thermal resistance, the particle size of the zinc oxide is 0.1 to 0.5 μm.

[0017] The present invention also provides a preparation method of a heat-conducting silicone grease with high heat conductivity and low thermal resistance, comprising the following steps:

[0018] Mix vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil on the side, hydrogen-containing silicone oil at the end, antioxidant, and coupling agent, and stir under vacuum for 16 - 25 min; then add aluminum powder and zinc oxide, and stir under vacuum for 27 - 38 min; then heat to 110 - 130 °C and stir under vacuum for 1.6 - 2.6 h; after cooling, add catalyst and inhibitor, and stir under vacuum for 25 - 40 min to obtain thermal conductive silicone grease.

[0019] As can be seen from the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) For the modified silicone oil of the present invention, through the combined use of multifunctional and multi-functional groups, firstly, the wettability of the silicone oil to the powder is improved, thereby enhancing the binding force between the oil and the powder. When resisting the stress generated by temperature cycling, there will be no interfacial separation between the oil and the powder, and problems such as drying and powdering will not occur; secondly, the dispersibility, fluidity, and interfacial wettability of the powder are improved, and the interfacial thermal resistance is reduced; in addition, the viscosity of the system is reduced, more powder can be filled, the thermal conductivity is increased, and the bulk thermal resistance is reduced.

[0021] (2) The present invention uses a combination of hydrogen-containing silicone oil on the side with a low hydrogen content and hydrogen-containing silicone oil at the end, which reacts with the main vinyl-terminated silicone oil, enabling the silicone oil molecules to have a certain degree of chain extension and cross-linking, increasing the molecular weight of the system, weakening the free path of molecular chain movement, and improving the anti-cracking ability; at the same time, due to its chain extension and micro-crosslinking reactions, it has a very strong adhesion to the application interface, can well absorb the stress generated by interface warping, and prevent interface delamination.

[0022] (3) The silicone grease prepared by the present invention through the modified silicone oil with multifunctional and multi-functional groups and the micro-crosslinking technology can obtain high thermal conductivity, low thermal resistance, and anti-pumping performance, greatly improving the application reliability of the silicone grease. Specific Embodiments

[0023] The present invention provides a thermal conductive silicone grease with high thermal conductivity and low thermal resistance, which is prepared from raw materials containing the following mass fractions:

[0024] 5 - 10 parts of vinyl-terminated silicone oil, 0.1 - 1 part of hydrogen-containing silicone oil on the side, 0.5 - 5 parts of hydrogen-containing silicone oil at the end, 0.5 - 2 parts of modified silicone oil, 0.1 - 1 part of antioxidant, 0.01 - 0.2 part of catalyst, 0.01 - 0.2 part of inhibitor, 0.2 - 1 part of coupling agent, 65 - 85 parts of aluminum powder, and 15 - 25 parts of zinc oxide.

[0025] In the present invention, the thermal conductive silicone grease is preferably prepared from raw materials comprising the following parts by mass: 5.4 to 9.6 parts of terminal vinyl silicone oil, 0.2 to 0.9 part of side hydrogen-containing silicone oil, 0.8 to 4.8 parts of terminal hydrogen-containing silicone oil, 0.7 to 1.9 parts of modified silicone oil, 0.2 to 0.7 part of antioxidant, 0.05 to 0.17 part of catalyst, 0.04 to 0.18 part of inhibitor, 0.3 to 0.8 part of coupling agent, 69 to 82 parts of aluminum powder, and 17 to 24 parts of zinc oxide;

[0026] More preferably, it is prepared from raw materials comprising the following parts by mass: 5.9 to 9.1 parts of terminal vinyl silicone oil, 0.4 to 0.8 part of side hydrogen-containing silicone oil, 1.4 to 4.2 parts of terminal hydrogen-containing silicone oil, 0.9 to 1.4 parts of modified silicone oil, 0.3 to 0.6 part of antioxidant, 0.08 to 0.14 part of catalyst, 0.07 to 0.16 part of inhibitor, 0.4 to 0.7 part of coupling agent, 72 to 80 parts of aluminum powder, and 19 to 23 parts of zinc oxide;

[0027] Even more preferably, it is prepared from raw materials comprising the following parts by mass: 7.3 parts of terminal vinyl silicone oil, 0.6 part of side hydrogen-containing silicone oil, 2.8 parts of terminal hydrogen-containing silicone oil, 1.2 parts of modified silicone oil, 0.5 part of antioxidant, 0.12 part of catalyst, 0.09 part of inhibitor, 0.6 part of coupling agent, 77 parts of aluminum powder, and 21 parts of zinc oxide.

[0028] In the present invention, the viscosity of the terminal vinyl silicone oil is preferably 100 to 200 mPa·s, more preferably 107 to 186 mPa·s, and even more preferably 112 mPa·s; the vinyl content of the terminal vinyl silicone oil is preferably 0.1 to 0.5 mmol / g, more preferably 0.2 to 0.4 mmol / g, and even more preferably 0.3 mmol / g.

[0029] In the present invention, the viscosity of the side hydrogen-containing silicone oil is preferably 200 to 1000 mPa·s, more preferably 212 to 974 mPa·s, and even more preferably 856 mPa·s; the hydrogen content of the side hydrogen-containing silicone oil is preferably 0.25 to 0.35 mmol / g, more preferably 0.27 to 0.34 mmol / g, and even more preferably 0.31 mmol / g.

[0030] In the present invention, the viscosity of the terminal hydrogen-containing silicone oil is preferably 20 to 500 mPa·s, more preferably 28 to 458 mPa·s, and even more preferably 289 mPa·s; the hydrogen content of the terminal hydrogen-containing silicone oil is preferably 0.5 to 1.5 mmol / g, more preferably 0.6 to 1.2 mmol / g, and even more preferably 0.9 mmol / g.

[0031] In the present invention, the viscosity of the modified silicone oil is preferably 100 to 600 mPa·s, more preferably 112 to 591 mPa·s, and still more preferably 346 mPa·s.

[0032] In the present invention, the modified silicone oil is preferably an end-side graft-modified silicone oil.

[0033] In the present invention, the functional groups grafted on the end side are preferably one or more of vinyl, long-chain alkyl groups with 6 to 16 carbon atoms, acrylate groups, methoxy groups, methacryloxy groups, epoxy groups, and 3-glycidylpropyl groups;

[0034] More preferably, when there are multiple functional groups grafted on the end side, the functional groups are vinyl, long-chain alkyl groups with 6 to 16 carbon atoms, acrylate groups, and methoxy groups; or vinyl, methoxy groups, long-chain alkyl groups with 6 to 16 carbon atoms, and methacryloxy groups; or vinyl, methoxy groups, epoxy groups, and 3-glycidylpropyl groups; or methoxy groups, long-chain alkyl groups with 6 to 16 carbon atoms, methacryloxy groups, and 3-glycidylpropyl groups.

[0035] In the present invention, the preparation method of the modified silicone oil is preferably as follows:

[0036] When grafting methoxy groups on the end side, the preparation method is: after the ring-opening reaction of the hydrogen-containing cyclic siloxane, methanol is used as a capping agent to graft methoxy groups at both ends of the silicone oil;

[0037] When grafting other functional groups except methoxy groups on the end side, the preparation method is: grafting functional groups on both sides of the silicone oil through a hydrosilylation reaction. The reaction conditions of the ring-opening reaction and the hydrosilylation reaction can be carried out by methods well known to those skilled in the art.

[0038] Taking the modified silicone oil grafted with methoxy groups, long-chain alkyl groups with 6 to 16 carbon atoms, methacryloxy groups, and 3-glycidylpropyl groups on the end side as an example, the preparation method is: after the ring-opening reaction of the hydrogen-containing cyclic siloxane, methanol is used as a capping agent to graft methoxy groups at both ends of the silicone oil, and then long-chain α-olefins, methacryloxy groups, and 3-glycidylpropyl groups are grafted with functional groups on both sides of the silicone oil through a hydrosilylation reaction, and the modified silicone oil is obtained after removing low boilers; the reaction process is as follows:

[0039]

[0040] Among them:

[0041] R is Me, Et or Ph; n = 3 to 7; m = 6 to 16; t = 1; a:b:c = 2:3:5.

[0042] In the present invention, the aluminum powder is preferably a mixture of spherical aluminum powder with a particle size of 0.5 to 3 μm and spherical aluminum powder with a particle size of 7 to 14 μm in a mass ratio of 1:2 to 1:4, more preferably 1:2.3 to 1:3.7, and still more preferably 1:3.5.

[0043] In the present invention, the particle size of zinc oxide is preferably 0.1 - 0.5 μm, more preferably 0.2 - 0.4 μm, and even more preferably 0.3 μm.

[0044] In the present invention, the antioxidant is preferably a phenolic antioxidant, more preferably isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0045] In the present invention, the coupling agent is preferably n-decyltriethoxysilane.

[0046] In the present invention, the catalyst is preferably a platinum catalyst, more preferably a Karstedt catalyst (platinum content is 3000 ppm).

[0047] In the present invention, the inhibitor is preferably an alkynol inhibitor, more preferably 1-ethynylcyclohexanol.

[0048] The present invention also provides a method for preparing a thermally conductive silicone grease with high thermal conductivity and low thermal resistance, comprising the following steps:

[0049] Mix vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil on the side, hydrogen-containing silicone oil at the end, antioxidant, and coupling agent, and stir under vacuum for 16 - 25 min; then add aluminum powder and zinc oxide, and stir under vacuum for 27 - 38 min; then heat to 110 - 130 °C and stir under vacuum for 1.6 - 2.6 h; after cooling, add the catalyst and inhibitor, and stir under vacuum for 25 - 40 min to obtain the thermally conductive silicone grease.

[0050] In the present invention, the vacuum degree of stirring under vacuum is preferably < -0.09 MPa.

[0051] In the present invention, the time for stirring the vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil on the side, hydrogen-containing silicone oil at the end, antioxidant, and coupling agent under vacuum is preferably 16 - 25 min, more preferably 17 - 24 min, and even more preferably 21 min; the rotation speed of stirring under vacuum is preferably 80 - 100 rpm, more preferably 83 - 97 rpm, and even more preferably 92 rpm.

[0052] In the present invention, the time for stirring under vacuum after adding aluminum powder and zinc oxide is preferably 27 - 38 min, more preferably 28 - 36 min, and even more preferably 34 min; the rotation speed of stirring under vacuum is preferably 20 - 60 rpm, more preferably 26 - 52 rpm, and even more preferably 38 rpm.

[0053] In the present invention, the heating temperature is preferably 110 - 130 °C, more preferably 112 - 127 °C, and even more preferably 121 °C.

[0054] In the present invention, the time of vacuum stirring after heating is preferably 1.6 to 2.6 h, more preferably 1.7 to 2.3 h, and still more preferably 1.9 h; the rotation speed of vacuum stirring is preferably 20 to 50 rpm, more preferably 22 to 49 rpm, and still more preferably 31 rpm.

[0055] In the present invention, the time of vacuum stirring after adding the catalyst and inhibitor is preferably 25 to 40 min, more preferably 29 to 39 min, and still more preferably 35 min; the rotation speed of vacuum stirring is preferably 20 to 60 rpm, more preferably 24 to 54 rpm, and still more preferably 44 rpm.

[0056] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Example 1

[0058] This example provides a heat-conducting silicone grease with high heat conductivity and low thermal resistance, which is prepared from raw materials containing the following mass fractions:

[0059] 6.5 parts of vinyl-terminated silicone oil (viscosity of 100 mPa·s, vinyl content of 0.1 mmol / g), 0.3 parts of side hydrogen-containing silicone oil (viscosity of 340 mPa·s, hydrogen content of 0.3 mmol / g), 1.9 parts of hydrogen-terminated silicone oil (viscosity of 95 mPa·s, hydrogen content of 0.9 mmol / g), 0.8 parts of modified silicone oil (viscosity of 400 mPa·s), 0.2 parts of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid isooctyl ester, 0.03 parts of platinum catalyst, 0.02 parts of 1-ethynylcyclohexanol, 0.25 parts of n-decyltriethoxysilane, 52 parts of 14-μm spherical aluminum powder, 19 parts of 3-μm spherical aluminum powder, and 19 parts of 0.4-μm zinc oxide;

[0060] Among them, the modified silicone oil is a modified silicone oil with vinyl, long-chain alkyl groups with 6 to 16 carbons, acrylate groups, and methoxy groups grafted on the ends and sides.

[0061] The preparation method of the above heat-conducting silicone grease includes the following steps:

[0062] Mix vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil with side groups, hydrogen-containing silicone oil with terminal groups, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and n-decyltriethoxysilane, and stir under vacuum at 80 rpm for 20 min; then add spherical aluminum powder and zinc oxide, and stir under vacuum at 45 rpm for 30 min; then heat to 120 °C and stir under vacuum at 30 rpm for 2.5 h; after cooling, add platinum catalyst and 1-ethynylcyclohexanol, and stir under vacuum at 40 rpm for 30 min to obtain thermal conductive silicone grease.

[0063] Example 2

[0064] This example provides a thermal conductive silicone grease with high thermal conductivity and low thermal resistance, which is prepared from raw materials containing the following mass fractions:

[0065] 8 parts of vinyl-terminated silicone oil (viscosity is 128 mPa·s, vinyl content is 0.3 mmol / g), 0.6 parts of hydrogen-containing silicone oil with side groups (viscosity is 600 mPa·s, hydrogen content is 0.26 mmol / g), 2.8 parts of hydrogen-containing silicone oil with terminal groups (viscosity is 120 mPa·s, hydrogen content is 1.1 mmol / g), 1.3 parts of modified silicone oil (viscosity is 525 mPa·s), 0.4 parts of isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 0.11 parts of platinum catalyst, 0.09 parts of 1-ethynylcyclohexanol, 0.8 parts of n-decyltriethoxysilane, 57 parts of 10-μm spherical aluminum powder, 18 parts of 1.5-μm spherical aluminum powder, and 24 parts of 0.3-μm zinc oxide;

[0066] Among them, the modified silicone oil is a modified silicone oil with vinyl, methoxy, long-chain alkyl groups with 6-16 carbons, and methacryloyloxy groups grafted at the ends and sides.

[0067] The preparation method of the above thermal conductive silicone grease includes the following steps:

[0068] Mix vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil with side groups, hydrogen-containing silicone oil with terminal groups, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and n-decyltriethoxysilane, and stir under vacuum at 90 rpm for 18 min; then add spherical aluminum powder and zinc oxide, and stir under vacuum at 50 rpm for 32 min; then heat to 117 °C and stir under vacuum at 27 rpm for 1.9 h; after cooling, add platinum catalyst and 1-ethynylcyclohexanol, and stir under vacuum at 32 rpm for 36 min to obtain thermal conductive silicone grease.

[0069] Example 3

[0070] This example provides a thermal conductive silicone grease with high thermal conductivity and low thermal resistance, which is prepared from raw materials containing the following mass fractions:

[0071] 6 parts of vinyl-terminated silicone oil (viscosity of 169 mPa·s and vinyl content of 0.5 mmol / g), 0.2 part of side hydrogen-containing silicone oil (viscosity of 485 mPa·s and hydrogen content of 0.31 mmol / g), 3.1 parts of hydrogen-terminated silicone oil (viscosity of 320 mPa·s and hydrogen content of 0.6 mmol / g), 1.5 parts of modified silicone oil (viscosity of 456 mPa·s), 0.7 part of isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 0.14 part of platinum catalyst, 0.09 part of 1-ethynylcyclohexanol, 0.6 part of n-decyltriethoxysilane, 58 parts of spherical aluminum powder with a diameter of 9.6 μm, 21 parts of spherical aluminum powder with a diameter of 2.3 μm, and 17 parts of zinc oxide with a diameter of 0.2 μm;

[0072] Among them, the modified silicone oil is a modified silicone oil with vinyl, methoxy, epoxy, and 3-glycidylpropyl grafted on the ends and sides.

[0073] The preparation method of the above thermal conductive silicone grease includes the following steps:

[0074] Mix the vinyl-terminated silicone oil, modified silicone oil, side hydrogen-containing silicone oil, hydrogen-terminated silicone oil, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and n-decyltriethoxysilane, and stir under vacuum at 94 rpm for 22 min; then add spherical aluminum powder and zinc oxide, and stir under vacuum at 56 rpm for 36 min; then heat to 126 °C and stir under vacuum at 35 rpm for 1.7 h; after cooling, add platinum catalyst and 1-ethynylcyclohexanol, and stir under vacuum at 35 rpm for 35 min to obtain the thermal conductive silicone grease.

[0075] Example 4

[0076] This example provides a thermal conductive silicone grease with high thermal conductivity and low thermal resistance, which is prepared from raw materials containing the following mass parts:

[0077] 5 parts of vinyl-terminated silicone oil (viscosity of 200 mPa·s and vinyl content of 0.2 mmol / g), 0.1 part of side hydrogen-containing silicone oil (viscosity of 960 mPa·s and hydrogen content of 0.35 mmol / g), 5 parts of hydrogen-terminated silicone oil (viscosity of 430 mPa·s and hydrogen content of 1.5 mmol / g), 2 parts of modified silicone oil (viscosity of 600 mPa·s), 1 part of isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 0.01 part of platinum catalyst, 0.01 part of 1-ethynylcyclohexanol, 1 part of n-decyltriethoxysilane, 60 parts of spherical aluminum powder with a diameter of 7 μm, 25 parts of spherical aluminum powder with a diameter of 0.5 μm, and 25 parts of zinc oxide with a diameter of 0.5 μm;

[0078] Among them, the modified silicone oil is a modified silicone oil with methoxy, long-chain alkyl with 6-16 carbons, methacryloyloxy, and 3-glycidylpropyl grafted on the ends and sides.

[0079] The preparation method of the above thermal conductive silicone grease comprises the following steps:

[0080] Mix vinyl-terminated silicone oil, modified silicone oil, hydrogen-containing silicone oil with side groups, hydrogen-containing silicone oil with terminal groups, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and n-decyltriethoxysilane, and stir under vacuum at 100 rpm for 25 min; then add spherical aluminum powder and zinc oxide, and stir under vacuum at 60 rpm for 38 min; then heat to 130 °C and stir under vacuum at 50 rpm for 2.6 h; after cooling, add a platinum catalyst and 1-ethynylcyclohexanol, and stir under vacuum at 60 rpm for 40 min to obtain the thermal conductive silicone grease.

[0081] Comparative Example 1

[0082] This comparative example provides a thermal conductive silicone grease, the raw material composition of which refers to Example 1, the difference being that it does not contain hydrogen-containing silicone oil with side groups and hydrogen-containing silicone oil with terminal groups.

[0083] Comparative Example 2

[0084] This comparative example provides a thermal conductive silicone grease, the raw material composition of which refers to Example 1, the difference being that it does not contain hydrogen-containing silicone oil with side groups.

[0085] Comparative Example 3

[0086] This comparative example provides a thermal conductive silicone grease, the raw material composition of which refers to Example 1, the difference being that it does not contain hydrogen-containing silicone oil with terminal groups.

[0087] Comparative Example 4

[0088] This comparative example provides a thermal conductive silicone grease, the raw material composition of which refers to Example 1, the difference being that the hydrogen-containing silicone oil with side groups is changed to 2.2 parts and the hydrogen-containing silicone oil with terminal groups is changed to 0 part.

[0089] Comparative Example 5

[0090] This comparative example provides a thermal conductive silicone grease, the raw material composition of which refers to Example 1, the difference being that it does not contain modified silicone oil.

[0091] Measure the thermal conductivity, viscosity, elastic modulus / viscous modulus of the thermal conductive silicone greases of Examples 1 to 4 and Comparative Examples 1 to 5, and the morphology of the thermal conductive silicone grease after the temperature cycle test (test conditions: maintain at -40 °C for 10 min, heat from -40 °C to 125 °C within 10 min, maintain at 125 °C for 10 min, this is one cycle, and there are 1000 cycles in total). The results are shown in Table 1.

[0092] Table 1 Performance test results of thermal conductive silicone grease

[0093]

[0094]

[0095] As can be seen from Table 1, the thermal conductivity of the thermal conductive silicone grease of the present invention is as high as 5.088 W / m·K, and the thermal resistance can be as low as 0.1 in*2℃ / W, having good high thermal conductivity, low thermal resistance and anti-pumping performance. However, due to the absence of side hydrogen-containing silicone oil and / or terminal hydrogen-containing silicone oil or excessive amount of side hydrogen-containing silicone oil in the thermal conductive silicone greases of Comparative Examples 1-4, problems such as cracking and delamination occurred, indicating that the combined use of side hydrogen-containing silicone oil and terminal hydrogen-containing silicone oil can improve the anti-cracking performance of the silicone grease. In Comparative Example 5, there is no modified silicone oil, and its thermal conductivity is significantly reduced, the thermal resistance is greatly increased, and delamination will also occur during the temperature cycle test, indicating that the use of modified silicone oil improves the thermal conductivity of the thermal conductive silicone grease.

[0096] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A thermal conductive silicone grease with high thermal conductivity and low thermal resistance, characterized in that, It is prepared from raw materials containing the following parts by mass: 5 - 10 parts of vinyl-terminated silicone oil, 0.1 - 1 part of side hydrogen-containing silicone oil, 0.5 - 5 parts of hydrogen-terminated silicone oil, 0.5 - 2 parts of modified silicone oil, 0.1 - 1 part of antioxidant, 0.01 - 0.2 part of catalyst, 0.01 - 0.2 part of inhibitor, 0.2 - 1 part of coupling agent, 65 - 85 parts of aluminum powder, 15 - 25 parts of zinc oxide; The viscosity of the modified silicone oil is 100 - 600 mPa·s; The modified silicone oil is a terminal-side linked grafted modified silicone oil, and the functional groups of the terminal-side link are vinyl, long-chain alkyl with 6 - 16 carbons, acrylate group and methoxy group; or vinyl, methoxy group, long-chain alkyl with 6 - 16 carbons and methacryloxy group; or vinyl, methoxy group, epoxy group and 3-glycidylpropyl; or methoxy group, long-chain alkyl with 6 - 16 carbons, methacryloxy group and 3-glycidylpropyl.

2. A thermal conductive silicone grease with high thermal conductivity and low thermal resistance according to claim 1, characterized in that, The viscosity of the vinyl-terminated silicone oil is 100 - 200 mPa·s, and the vinyl content of the vinyl-terminated silicone oil is 0.1 - 0.5 mmol / g.

3. A thermal conductive silicone grease with high thermal conductivity and low thermal resistance according to claim 1 or 2, characterized in that The viscosity of the side hydrogen-containing silicone oil is 200 - 1000 mPa·s, and the hydrogen content of the side hydrogen-containing silicone oil is 0.25 - 0.35 mmol / g.

4. A thermal conductive silicone grease with high thermal conductivity and low thermal resistance according to claim 3, characterized in that, The viscosity of the hydrogen-terminated silicone oil is 20 - 500 mPa·s, and the hydrogen content of the hydrogen-terminated silicone oil is 0.5 - 1.5 mmol / g.

5. A thermal grease with high thermal conductivity and low thermal resistance according to claim 1, characterized in that, The aluminum powder is a mixture of spherical aluminum powder with a size of 0.5 - 3 μm and spherical aluminum powder with a size of 7 - 14 μm in a mass ratio of 1:2 - 1:

4.

6. A heat-conducting silicone grease with high thermal conductivity and low thermal resistance according to claim 1, 4 or 5, characterized in that The particle size of the zinc oxide is 0.1 - 0.5 μm.

7. A method for preparing a highly thermally conductive and low thermal resistance thermal grease according to any one of claims 1 to 6, characterized in that, It includes the following steps: Mix the vinyl-terminated silicone oil, modified silicone oil, side hydrogen-containing silicone oil, hydrogen-terminated silicone oil, antioxidant, and coupling agent, and stir under vacuum for 16 - 25 min; then add aluminum powder and zinc oxide, and stir under vacuum for 27 - 38 min; then heat to 110 - 130 °C and stir under vacuum for 1.6 - 2.6 h; after cooling, add the catalyst and inhibitor, and stir under vacuum for 25 - 40 min to obtain the thermal conductive silicone grease.

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